Trains are leaving station A for station B every 15 minutes starting 8:00 am. The distance between the stations is 80 km. If a train leaves station B for station A at 11:05 am, how many oncoming trains will it meet?
1. Trains from station A to station B travel at 40 kmh
2. The train from station B to station A travels at 40 kmh
I would go with C.
You need to know how many trains going from A to B are on the tracks 3 hours and 5 minutes after 8am. This requires you to know (1).
But that is not enough. You also need to know how many trains depart from station A in between 11:05 and the train's arrival at Station A. For this, you need to know how long the train takes to travel from B to A.